Noninvasive Hemodynamic Evaluation Research Articles

Image2Flow: A proof-of-concept hybrid image and graph convolutional neural network for rapid patient-specific pulmonary artery segmentation and CFD flow field calculation from 3D cardiac MRI data.

Computational fluid dynamics (CFD) can be used for non-invasive evaluation of hemodynamics. However, its routine use is limited by labor-intensive manual segmentation, CFD mesh creation, and time-consuming simulation. This study aims to train a deep learning model to both generate patient-specific volume-meshes of the pulmonary artery from 3D cardiac MRI data and directly estimate CFD flow fields. This proof-of-concept study used 135 3D cardiac MRIs from both a public and private dataset. The pulmonary arteries in the MRIs were manually segmented and converted into volume-meshes. CFD simulations were performed on ground truth meshes and interpolated onto point-point correspondent meshes to create the ground truth dataset. The dataset was split 110/10/15 for training, validation, and testing. Image2Flow, a hybrid image and graph convolutional neural network, was trained to transform a pulmonary artery template to patient-specific anatomy and CFD values, taking a specific inlet velocity as an additional input. Image2Flow was evaluated in terms of segmentation, and the accuracy of predicted CFD was assessed using node-wise comparisons. In addition, the ability of Image2Flow to respond to increasing inlet velocities was also evaluated. Image2Flow achieved excellent segmentation accuracy with a median Dice score of 0.91 (IQR: 0.86-0.92). The median node-wise normalized absolute error for pressure and velocity magnitude was 11.75% (IQR: 9.60-15.30%) and 9.90% (IQR: 8.47-11.90), respectively. Image2Flow also showed an expected response to increased inlet velocities with increasing pressure and velocity values. This proof-of-concept study has shown that it is possible to simultaneously perform patient-specific volume-mesh based segmentation and pressure and flow field estimation using Image2Flow. Image2Flow completes segmentation and CFD in ~330ms, which is ~5000 times faster than manual methods, making it more feasible in a clinical environment.

Unraveling diurnal and technical variability in cerebral hemodynamics from neurovascular 4D-Flow MRI

Neurovascular 4D-Flow MRI enables non-invasive evaluation of cerebral hemodynamics including measures of cerebral blood flow (CBF), vessel pulsatility index (PI), and cerebral pulse wave velocity (PWV). 4D-Flow measures have been linked to various neurovascular disorders including small vessel disease and Alzheimer’s disease; however, physiological and technical sources of variability are not well established. Here, we characterized sources of diurnal physiological and technical variability in cerebral hemodynamics using 4D-Flow in a retrospective study of cognitively unimpaired older adults (N = 750) and a prospective study of younger adults (N = 10). Younger participants underwent repeated MRI sessions at 7am, 4 pm, and 10 pm. In the older cohort, having an MRI earlier on the day was significantly associated with higher CBF and lower PI. In prospective experiments, time of day significantly explained variability in CBF and PI; however, not in PWV. Test-retest experiments showed high CBF intra-session repeatability (repeatability coefficient (RPC) =7.2%), compared to lower diurnal repeatability (RPC = 40%). PI and PWV displayed similar intra-session and diurnal variability (PI intra-session RPC = 22%, RPC = 24% 7am vs 4 pm; PWV intra-session RPC = 17%, RPC = 21% 7am vs 4 pm). Overall, CBF measures showed low technical variability, supporting diurnal variability is from physiology. PI and PWV showed higher technical variability but less diurnal variability.

The EVA Study: Early Vascular Aging in Women With History of Preeclampsia.

Background Early vascular aging (EVA) is associated with higher risk of adverse cardiovascular events and can be estimated noninvasively by assessing arterial hemodynamics. Women with a history of preeclampsia have increased risk of cardiovascular disease, but underlying mechanisms are incompletely understood. We hypothesized that women with a history of preeclampsia display persistent arterial abnormalities and EVA in the postpartum period. Methods and Results We performed a comprehensive, noninvasive arterial hemodynamic evaluation in women with a history of preeclampsia (n=40) and age-matched controls with previous normotensive pregnancies (n=40). We used validated methods integrating applanation tonometry with transthoracic echocardiography to obtain measures of aortic stiffness, steady and pulsatile arterial load, central blood pressure, and arterial wave reflections. Presence of EVA was defined as aortic stiffness higher than that predicted from reference values based on the participant's age and blood pressure. The association of preeclampsia with arterial hemodynamic variables was assessed with multivariable linear regression, and the association of severe preeclampsia with EVA was assessed with multivariable logistic regression, adjusted for confounders. We found that women with a history of preeclampsia had greater aortic stiffness, steady arterial load, central blood pressure, and arterial wave reflections when compared with controls. We observed a dose-response relationship, with the greatest abnormalities observed in subgroups with severe, preterm, or recurrent preeclampsia. Women with severe preeclampsia had 9.23 times greater odds of having EVA as compared with controls (95% CI, 1.67-51.06, P=0.011) and 7.87 greater odds of EVA as compared with women with nonsevere preeclampsia (95% CI, 1.29-47.77, P=0.025). Conclusions Our study comprehensively characterizes arterial hemodynamic abnormalities after preeclampsia and suggests that specific subgroups of women with a history of preeclampsia exhibit greater alterations in arterial hemodynamics related to arterial health. Our findings have important implications for understanding potential links between preeclampsia and cardiovascular events, and suggest women with severe, preterm, or recurrent preeclampsia as subgroups who may deserve intensification of efforts for prevention and early detection of cardiovascular disease.

Noninvasive Hemodynamic Evaluation Following TAVI for Severe Aortic Stenosis.

Background Various hemodynamic changes occur following transcatheter aortic valve implantation (TAVI) that may impact therapeutic decisions. NICaS is a noninvasive bioimpedance monitoring system aimed at hemodynamic assessment. We used the NICaS system in patients with severe aortic stenosis (AS) to evaluate short-term hemodynamic changes after TAVI. Methods and Results We performed hemodynamic analysis using NICaS on 97 patients with severe AS who underwent TAVI using either self-expandable (68%) or balloon-expandable (32%) valves. Patients were more often women (54%) and had multiple comorbidities including hypertension (83%), coronary artery disease (46%), and diabetes (37%). NICaS was performed at several time points-before TAVI, soon after TAVI, at hospital discharge, and during follow-up. Compared with baseline NICaS measurements, we observed a significant increase in systolic blood pressure and total peripheral resistance (systolic blood pressure 132±21 mm Hg at baseline versus 147±23 mm Hg after TAVI, P<0.001; total peripheral resistance 1751±512 versus 2084±762 dynes*s/cm5, respectively, P<0.001) concurrent with a decrease in cardiac output and stroke volume (cardiac output 4.2±1.5 versus 3.9±1.3 L/min, P=0.037; stroke volume 61.4±14.8 versus 56.2±15.9 mL, P=0.001) in the immediate post-TAVI period. At follow-up (median 59 days [interquartile range, 40.5-91]) these measurements returned to values that were not different from the baseline. A significant improvement in echocardiography-based left ventricular ejection fraction was observed from baseline to follow-up (55.6%±11.6% to 59.4%±9.4%, P<0.001). Conclusions Unique short-term adaptive hemodynamic changes were observed using NICaS in patients with AS soon after TAVI. Noninvasive hemodynamic evaluation immediately following TAVI may contribute to the understanding of complex hemodynamic changes and merits favorable consideration.

Assessment of Indices of Conjunctival Microvascular Function in Patients With and Without Obstructive Coronary Artery Disease

BackgroundAtherosclerotic heart disease often remains asymptomatic until presentation with a major adverse cardiovascular event. Primary preventive therapies improve outcomes, but conventional screening often misattributes risk. Vascular imaging can be utilised to detect atherosclerosis, but often involves ionising radiation. The conjunctiva is a readily accessible vascular network allowing non-invasive hemodynamic evaluation. AimTo compare conjunctival microcirculatory function in patients with and without obstructive coronary artery disease. MethodsWe compared the conjunctival microcirculation of myocardial infarction patients (MI-cohort) to controls with no obstructive coronary artery disease (NO-CAD cohort). Conjunctival imaging was performed using a smartphone and slit-lamp biomicroscope combination. Microvascular indices of axial (Va) and cross-sectional (Vcs) velocity; blood flow rate (Q); and wall shear rate (WSR) were compared in all conjunctival vessels between 5 and 45 μm in diameter. ResultsA total of 127 patients were recruited (66 MI vs 61 NO-CAD) and 3602 conjunctival vessels analysed (2414 MI vs 1188 NO-CAD). Mean Va, Vcs and Q were significantly lower in the MI vs NO-CAD cohort (Va 0.50 ± 0.17 mm/s vs 0.55 ± 0.15 mm/s, p < 0.001; Vcs 0.35 ± 0.12 mm/s vs 0.38 ± 0.10 mm/s, p < 0.001; Q 154 ± 116 pl/s vs 198 ± 130 pl/s, p < 0.001). To correct for differences in mean vessel diameter, WSR was compared in 10–36 μm vessels (3268/3602 vessels) and was lower in the MI-cohort (134 ± 64 s−1 vs 140 ± 63 s−1, p = 0.002). ConclusionsConjunctival microcirculatory alterations can be observed in patients with obstructive coronary artery disease. The conjunctival microvasculature merits further evaluation in cardiovascular risk screening.

831 ECHO-API: CORRELATION WITH INVASIVE API AND PROGNOSTIC ROLE IN HEART FAILURE

Abstract Background The benefit of invasive hemodynamic assessment in the setting of heart failure (HF) is still controversial. Increased right and left filling pressure have been shown to be associated with adverse prognosis, while reduced cardiac index (CI) has not. For this reason, novel hemodynamic indexes have been developed aiming to better describe the cardiac function in different loading conditions. In this context, the aortic pulsatility index (API) is a hemodynamic variable integrating LV function and loading condition which has the potential to better predict clinical outcome. It is calculated as systolic blood pressure (SBP) minus diastolic blood pressure (DBP) divided by pulmonary capillary wedge pressure (PCWP); the difference between SBP and DBP, known as arterial pulse pressure, correlates with SV, while PCWP is a marker of the degree of pulmonary congestion. API has been shown to predict long-term outcomes in acute decompensated HF and advanced HF cohorts. To the best of our knowledge, hemodynamically-derived API has never been compared to echocardiography-estimated API. Purpose To evaluate the accuracy of API obtained with echocardiographic methods (echo-API) compared with the invasive hemodynamic measure obtained with right heart catheterization (RHC) and to explore its prognostic role in a HF cohort. Methods Consecutive patients referred for RHC to Città della Salute e della Scienza hospital from May 2019 to August 2022 underwent complete two-dimensional echocardiographic evaluation and RHC. Patients ≥ 18 years with either acute or chronic HF, irrespective of etiology, were included. For the calculation of Echo-API PCWP was estimated using the average E/e’ ratio. The association between echo-API with MACE (composite of death, LVAD implantation or heart transplantation) at 1 year follow-up was evaluated. Results 112 patients were included in the analysis. They were mostly male, mean age was 57 years and the underlying heart disease was predominantly idiopathic dilated cardiomyopathy (32%), followed by ischemic (30%); mean LVEF was 35,07%. Mean Echo-API was 3,54. Echo-API showed a significant correlation with invasive API using the Pearson correlation coefficient (r = 0,6591, 95% CI 0,4639–0,7933, p &amp;lt; 0,0001) and showed a linear correlation at Bland-Altman plot. At multivariate regression analysis Echo-API was significatively associated with primary outcome (OR 0.469, 95% CI 0.26–0.84, p 0,011). Conclusions Echocardiographically-derived aortic pulsatility index can be obtained in all patients with advanced HF and shows a good correlation with invasive API; it is associated with MACE, representing a useful tool for non-invasive hemodynamic evaluation and risk stratification.

Use of a novel handheld ultrasound device with continuous-wave doppler capability for the assessment of valvular heart disease

Abstract Background/Introduction Echocardiography is the primary non-invasive imaging method for the diagnosis and evaluation of valvular heart disease. Doppler echocardiography provides accurate non-invasive evaluation of valve hemodynamics. Recent technological advancements have enabled the acquisition of echocardiographic images at the point-of-care by using small handheld ultrasound devices (HUDs); their availability and relatively low cost compared to the high-end systems have made these devices attractive to use for rapid medical decision making. However, the inability to quantify flow velocity has been a major limitation for HUDs; the lack of spectral Doppler capability has so far hindered the comprehensive assessment of haemodynamic data and valve function. Purpose To evaluate for the first time the accuracy of a novel HUD with continuous-wave (CW) Doppler capability to measure flow velocity in valvular heart disease. Methods We prospectively included 56 consecutive patients who were referred to the echocardiography laboratory of a tertiary hospital. All patients were scanned with both the Kosmos HUD and the standard echocardiography cart-based system (reference standard) in a randomized order. CW Doppler measurements of maximum velocities (Vmax) were obtained from the apical five-chamber view for the aortic ejection and regurgitation and from the apical four-chamber view for the mitral and tricuspid regurgitation (presence assessed by colour Doppler), maintaining a parallel orientation between the ultrasound beam and the blood flow. All measurements were compared to assess inter-method agreement using linear regression and Bland-Altman analysis. Results The acquisition of CW Doppler signal using the HUD was feasible in 55 out of 56 patients (mean age 66±16 years old, 40% female). Among them, there were 31 cases of (at least mild) aortic stenosis and 23 cases of valvular regurgitation (4 aortic, 6 mitral and 13 tricuspid regurgitations). There was excellent correlation between the HUD and the cart-based system CW Doppler for the aortic Vmax measurements (r=0.99, p&amp;lt;0.001) and for the valvular regurgitation Vmax measurements (r=0.98, p&amp;lt;0.001). The corresponding Bland-Altman plots showed a small underestimation bias of −0.13 m/sec (p&amp;lt;0.001), with limits of agreement ±0.41 m/sec for the aortic Vmax and −0.21 m/sec (p=0.003), with limits of agreement ±0.57 m/sec for the valvular regurgitation Vmax measurements. Conclusion A novel HUD with CW Doppler spectral analysis was able to provide peak jet velocity measurements comparable to the standard cart-based echocardiography systems, in patients with valvular stenosis and regurgitation. Such expanded capabilities of HUDs show clinical potential and may lead to the improvement of the assessment of valvular pathology at the point-of-care. Funding Acknowledgement Type of funding sources: None.

Hemodynamic assessment in patients with preterm premature rupture of the membranes (pPROM)

ObjectiveThe aim of this study was to assess the hemodynamic differences in women with pPROM versus physiological pregnancies. Study designThis was a prospective case control study of 15 patients with pPROM and 45 controls. Patients and controls were submitted at enrollment to a non-invasive hemodynamic evaluation with UltraSonic Cardiac Output Monitor (USCOM), and to blood tests to check white blood cells count and C-reactive protein (CRP) levels. We followed pPROM patients until delivery noting fetal/neonatal and maternal unfavorable outcomes (maternal fever, APGAR 1′ and 5′< 7, stillbirth). ResultsPatients with pPROM showed higher values of cardiac output (9.1 ± 2.3 vs 7.1 ± 0.85, p < 0.01), lower systemic vascular resistances (792.1 ± 162 vs 1006.2 ± 110.7, p < 0.01), higher minute distance (32.3 ± 7.8 vs 25 ± 2.8, p < 0.01), lower Potential to Kinetic Energy Ratio (16.5 ± 5.3 vs 22.4 ± 6.8, p < 0.01), higher heart rate (97.5 ± 15.4 vs 82.4 ± 12, p < 0.01) and higher oxygen delivery (1313.2 ± 325.8 vs 1080.7 ± 151.8, p < 0.01) vs. controls. Six out of 15 pPROM patients had an unfavorable outcome. There were no significant differences in CRP levels and WBC count at admission in the two pPROM subgroups, whereas maternal hemodynamics was characterized by lower SVR (718 ± 72 vs 863 ± 123, p = 0.02) in subsequently complicated patients. ConclusionsMaternal hemodynamics is altered in pPROM patients, with a lower Systemic Vascular Resistance and higher Cardiac Output vs. controls. This hyperdynamic circulation appears to anticipates the changes of serum markers of inflammation (CRP, WBC count) and seems to be more pronounced at admission in pPROM patients developing unfavorable outcomes.

Non-invasive hemodynamic evaluation following TAVI for severe aortic stenosis

Abstract Funding Acknowledgements Type of funding sources: None. Background Various hemodynamic changes occur following Transcatheter aortic valve implantation (TAVI) that impact treatment decisions. NICaS, a noninvasive whole-body bio-impedance monitoring system to assess hemodynamics and fluid balance, was tested in patients with severe aortic stenosis (AS) before and after TAVI. Methods Between October 2019 and December 2020 all consecutive patients with severe AS undergoing TAVI were assessed by NICaS at several time points – 24 hours before (baseline) and after the procedure, at hospital discharge and at 30 days to 1 year follow-up. Excluded were patients undergoing TAVI due to reasons other than severe AS, patients under general anesthesia and those who died at the catheterization lab or immediately following the procedure. Results We performed hemodynamic analysis on 97 consecutive patients who underwent TAVI using either Medtronic Evolut R (54%), Edwards Sapien 3 (32%) or SYMETIS ACURATE neo (13%). Patients were more often women (54%) and had multiple comorbidities including hypertension (83%), dyslipidemia (79%), coronary artery disease (46%), and diabetes mellitus (37%). Compared to baseline NICaS measurements, we observed increases in systolic blood pressure (BP) and total peripheral resistance (TPR) within 24 hours following TAVI (systolic BP 132.5±22.3 mmHg at baseline versus 148.4±23.9 mmHg after TAVI, P&amp;lt;0.001; TPR 1754±520 versus 2094±752 dynes*s/cm5, respectively, P&amp;lt;0.001) while cardiac output (CO), cardiac index (CI) and stroke volume (SV) decreased (CO 4.2±1.2 versus 3.9±1.2 L/min, respectively, P=0.013; SV 62±15 versus 56±15.8 mL, P=0.002). However, opposite trends were demonstrated exclusively in patients with ejection fraction (EF) under 40%. At follow-up (median 59 days, IQR [39.5-91]) these hemodynamic measurements returned to values that were not statistically different from the baseline, despite a significant improvement in EF from baseline to follow-up (55.6±11.6 to 59.4±9.4%, P&amp;lt;0.001). Conclusion A unique pattern of short and longer term adaptive hemodynamic changes was demonstrated using the NICaS system among patients undergoing TAVI. These findings require validation and further research to their underlying mechanism if NICaS is to be used as a bedside monitoring tool to guide treatment decisions.

Clinical and Prognostic Role of Noninvasive Hemodynamic Assessment in Left Ventricular Assist Device Carriers.

Persistence of heart failure symptoms or suboptimal hemodynamic is a frequent condition in LVAD carriers, associated with adverse outcome. Invasive hemodynamic optimization was associated with a better outcome. Our group recently validated an echocardiographic protocol to noninvasively assess hemodynamics of LVAD patients. Aim of this prospective study was to investigate its utility in clinical practice and its prognostic role. From February 2016 to February 2019 fifty-five LVAD carriers (HVAD/HM3 34/21; age 61 ± 10 years, 89% males; INTERMACS profile at LVAD implantation ≤3 68%). A two-phased protocol was performed. First, the patient underwent clinical evaluation. Second, an echo-Doppler blinded to clinical data was performed. Clinical and echo-Doppler evaluation both identified patients with "optimal hemodynamic profile" (normal left and right estimated atrial pressures) versus other profiles. clinical evaluation overestimated the presence of an optimal profile compared with echo-Doppler (83% vs. 59%). The presence of overt heart failure identified patients with the highest risk of adverse outcomes (death or hospitalization for HF at 6 months: HR 15, 95% CI, 5.5-39, P < 0.001). An optimal profile by echo-Doppler was associated with a better outcome among patients without overt heart failure (death or hospitalization for HF at 6 months: HR 0.08, 95% CI, 0.01.5-0.64, P < 0.02). After echo-Doppler, the clinician modified treatment in 46 cases (37%). Noninvasive evaluation of hemodynamics by echo-Doppler adds significant prognostic information in LVAD patients without overt HF and is a valuable tool to tailor treatment in the outpatient follow-up of LVAD carriers. Visual abstract: http://links.lww.com/ASAIO/A783.

Noninvasive Morphologic and Hemodynamic Evaluation of Type B Aortic Dissection: State of the Art and Future Perspectives.

Stanford type B aortic dissection (TBAD) is associated with relatively high rates of morbidity and mortality, and appropriate treatment selection is important for optimizing patient outcomes. Depending on individualized risk factors, clinical presentation, and imaging findings, patients are generally stratified to optimal medical therapy anchored by antihypertensives or thoracic endovascular aortic repair (TEVAR). Using standard anatomic imaging with CT or MRI, several high-risk features including aortic diameter, false lumen (FL) features, size of entry tears, involvement of major aortic branch vessels, or evidence of visceral malperfusion have been used to select patients likely to benefit from TEVAR. However, even with these measures, the number needed to treat for TEVAR remains, and improved risk stratification is needed. Increasingly, the relationship between FL hemodynamics and adverse aortic remodeling in TBAD has been studied, and evolving noninvasive techniques can measure numerous FL hemodynamic parameters that may improve risk stratification. In addition to summarizing the current clinical state of the art for morphologic TBAD evaluation, this review provides a detailed overview of noninvasive methods for TBAD hemodynamics characterization, including computational fluid dynamics and four-dimensional flow MRI. Keywords: CT, Image Postprocessing, MRI, Cardiac, Vascular, Aorta, Dissection © RSNA, 2021.

RELATIONSHIP BETWEEN 24-HOURS URINARY SODIUM EXCRETION AND ARTERIAL STIFFNESS IN CONTROLLED HYPERTENSIVE AND RESISTANT HYPERTENSIVE INDIVIDUALS

Objective: To compare the influence of dietary sodium intake through 24-hours urinary sodium excretion (Na + Ur24 h) on arterial stiffness markers in controlled and resistant hypertensive individuals. Design and method: 126 patients were randomized in an observational and cross-sectional study, divided into two groups: 63 in the controlled hypertension group (CHTN) and 63 in the resistant hypertension group (RHTN). All were submitted to clinical evaluation, laboratory tests, Na + Ur24 h and non-invasive central hemodynamic evaluation by the SphygmoCor® and Mobil-O-Graph® system to determine arterial stiffness parameters. Results: Clinical characteristics and laboratory tests were similar in both groups. There was no statistical significance between CHTN and RHTN for Na + Ur24 h values (186.60 ± 92.15 vs.179.76 ± 66.91 mEq/L, respectively). The carotid-femoral pulse wave velocity (cfPWVc) showed no statistically significant difference between CHTN and RHTN (10.52 ± 2.47 m/s vs. 10.21 ± 2.27 m/s, respectively). Central hemodynamic parameters were statistically different between the groups assessed by 24-hour ambulatory blood pressure monitoring (ABPM - Mobil-O-Graph®). RHTN group had higher cardiac output during sleep and greater vascular resistance during wakefulness and 24 hours than CHTN group (p &lt; 0.05) in ABPM. Conclusions: Na + Ur24 h excretion is similar between groups, but there is better adherence to dietary sodium intake restriction in the resistant hypertension group. Physiological hemodynamic parameters are altered in the RHTN group, such as cardiac output and peripheral vascular resistance, a fact that evidences their participation in the pathophysiological process of resistant hypertension.

Characterization of the ischemic muscle by quantitative hybrid diffuse optical measurement

The ischemia is one of the most common and severe events threatening the function and maintenance of organs and limbs, while there is not ideal non-invasive method to distinguish and quantify the ischemia. The near-infrared light techniques permit noninvasive evaluation of microvascular hemodynamics of muscle, but most of studies measure the relative hemodynamic changes, that is, it needs the same normal tissue from the same subject as the reference measurement. In this study, the quantitative hemodynamic values of the total hemoglobin concentration (HbT), tissue oxygen saturation (StO2) and blood flow index (BFI) were monitored simultaneously by the custom hybrid diffuse optical device based on the combining of near infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS). A vascular occlusion test (VOT) on the forearm was utilized to produce transient controlled ischemia with arm cuff inflated to the pressure of 200 mmHg. The statistical significances (p value) were calculated by the pair sample t-test method and the receiver operator characteristic curves (ROCs) for the derived quantitative hemodynamic parameters between the normal tissue and the ischemic muscle. The results from fifteen subjects show both of the quantitative values of BFI and StO2 can distinguish the ischemia from normal tissue through putting the probe on the muscle tissue without reference measurement. The BFI has best discrimination ability and the optimal condition to derive the BFI is using the assumed same optical properties for all the subjects rather than the derived individual optical properties from each subject. The StO2 can also distinguish the ischemia and the optimal condition to derive the StO2 is using the derived individual reduced scattering coefficient from each subject rather than the assumed same reduced scattering coefficient for all the subjects. Therefore the hybrid diffuse optical device may be better than the usual NIRS device to monitor the state of ischemia of tissue and BFI is the promising biomarker to distinguish and quantify the ischemia.

Noninvasive Pulmonary Hemodynamic Evaluation in Athletes With Exercise-Induced Hypoxemia

Pulmonary capillary stress failure is potentially involved in exercise-induced hypoxemia (ie, a significant fall in hemoglobin oxygen saturation [Spo2]) during sea level exercise in endurance-trained athletes. It is unknown whether there are specific properties of pulmonary vascular function in athletes exhibiting oxygen desaturation. Ten endurance-trained athletes with exercise-induced hypoxemia (EIH), nine endurance-trained athletes with no exercise-induced hypoxemia (NEIH), and 10 untrained control subjects underwent an incremental exercise stress echocardiography coupled with lung diffusion capacity for carbon monoxide (Dlco) and lung diffusion capacity for nitric oxide (Dlno) testing. Functional adaptation of the pulmonary circulation was evaluated with measurements of mean pulmonary arterial pressure (mPAP), pulmonary capillary pressure, pulmonary vascular resistance (PVR), cardiac output (Qc), and pulmonary vascular distensibility (alpha) mathematically determined from the curvilinearity of the multi-point mPAP/Qc relation. EIH athletes exhibited a lower exercise-induced PVR decrease compared with the untrained and NEIH groups (P< .001). EIH athletes showed higher maximal mPAP compared with NEIH athletes (45.4 ± 0.9mmHg vs41.6 ± 0.9mmHg, respectively; P= .003); there was no difference between the NEIH and untrained subjects. Alpha was lower in the EIH group compared with the NEIH group (P< .05). Maximal mPAP, Pcap, and alpha were correlated with the fall of Spo2 during exercise (P< .01, P< .01, and P< .05). Dlno and Dlco increased with exercise in all groups, with no differences between groups. Dlno/Qc was correlated to the exercise-induced Spo2 changes (P< .05). EIH athletes exhibit higher maximal pulmonary vascular pressures, lower vascular distensibility, or exercise-induced changes in PVR compared with NEIH subjects, in keeping with pulmonary capillary stress failure or intrapulmonary shunting hypotheses.

Long-term Non-invasive Hemodynamic Evaluation of Left Endocardial Cardiac Resynchronization Therapy

Introduccion: La VAB es una cardiopatia congenita que puede asociarse a complicaciones aorticas y/o valvulares. Resulta importante identificar grupos de riesgo, para realizar un seguimiento mas estrecho e indicar la intervencion a tiempo. El siguiente trabajo busca analizar el impacto que tienen las caracteristicas clinicas y morfologicas valvulares en el desarrollo de disfuncion valvular aortica moderada/severa (significativa) y en la incidencia de eventos cardiovasculares mayores en adultos con VAB. Materiales y metodos: Se incluyeron pacientes consecutivos con diagnostico de VAB no sindromatica (2010-2019) en seguimiento en nuestra institucion. Se recabo informacion clinica y ecocardiografica de manera prospectiva. Se realizo analisis uni y multivariado para identificar caracteristicas clinicas y morfologicas predictoras de disfuncion valvular significativa y de eventos cardiovasculares mayores (muerte/cirugia/sindrome aortico). Una p menor 0,05 fue considerada significativa. Resultados: Se incluyeron 300 pacientes (44.3±15.3 anos, 71% hombres). La mayoria con VAB tipo I y presencia de rafe (79.6% y 77%, respectivamente). La edad media de diagnostico fue de 36.3 ±16.2 anos. Hubo 84 pacientes (31.2%) que presentaban disfuncion valvular aortica significativa al momento del inicio del estudio. Con un seguimiento a 4.9 ± 1.7 anos, 23 pacientes requirieron cirugia cardiaca (7.7%) y 3 fallecieron (1%). Al final del seguimiento 101 (33.6%) pacientes presentaban disfuncion valvular aortica significativa. La presencia de al menos 1 de los siguientes factores: prolapso valvular, calcificacion valvular aortica basal >1 y una edad > 50 anos se asocio a menor sobrevida libre de disfuncion valvular aortica significativa y de eventos mayores. Conclusiones: En nuestra cohorte, observamos una alta incidencia de eventos asociados a VAB. Dentro de las variables analizadas, la presencia de al menos 1 factor de riesgo se asocio a menor sobrevida libre de eventos mayores y disfuncion significativa a 4,9 anos.

Cardiac output measurements via echocardiography versus thermodilution: A systematic review and meta-analysis.

Echocardiography, as a noninvasive hemodynamic evaluation technique, is frequently used in critically ill patients. Different opinions exist regarding whether it can be interchanged with traditional invasive means, such as the pulmonary artery catheter thermodilution (TD) technique. This systematic review aimed to analyze the consistency and interchangeability of cardiac output measurements by ultrasound (US) and TD. Five electronic databases were searched for studies including clinical trials conducted up to June 2019 in which patients’ cardiac output was measured by ultrasound techniques (echocardiography) and TD. The methodological quality of the included studies was evaluated by two independent reviewers who used the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2), which was tailored according to our systematic review in Review Manager 5.3. A total of 68 studies with 1996 patients were identified as eligible. Meta-analysis and subgroup analysis were used to compare the cardiac output (CO) measured using the different types of echocardiography and different sites of Doppler use with TD. No significant differences were found between US and TD (random effects model: mean difference [MD], -0.14; 95% confidence interval, -0.30 to 0.02; P = 0.08). No significant differences were observed in the subgroup analyses using different types of echocardiography and different sites except for ascending aorta (AA) (random effects model: mean difference [MD], -0.37; 95% confidence interval, -0.74 to -0.01; P = 0.05) of Doppler use. The median of bias and limits of agreement were -0.12 and ±0.94 L/min, respectively; the median of correlation coefficient was 0.827 (range, 0.140–0.998). Although the difference in CO between echocardiography by different types or sites and TD was not entirely consistent, the overall effect of meta-analysis showed that no significant differences were observed between US and TD. The techniques may be interchangeable under certain conditions.

From left ventricular ejection fraction to cardiac hemodynamics: role of echocardiography in evaluating patients with heart failure.

In clinical practice heart failure (HF) patients are generally classified on the basis of left ventricular (LV) ejection fraction. This approach, however, has important limitations. According to the definition of HF as a clinical syndrome that results from any impairment of LV filling or ejection of blood, a more articulated hemodynamic categorization of HF patients taking into account both LV forward flow and filling pressure would be desirable. However, the reliability of hemodynamic measures using echocardiographic techniques, which are the most used in current clinical practice for evaluation of HF patients, needs to be clarified. The aim of this article, therefore, is to verify whether echocardiography has acceptable feasibility, accuracy and reproducibility for the noninvasive evaluation of LV hemodynamics. This evaluation is necessary to progress to a hemodynamic characterization of HF patients that would ultimately overcome the HF classification based on ejection fraction.

Feasible study of carotid artery Doppler ultrasound blood flow measurement during chest compression cardiopulmonary resuscitation

To determine the feasibility of ultrasound to measure blood flow on patients with chest compression cardiopulmonary resuscitation (CPR), and to find out a real-time, noninvasive hemodynamic evaluation method. A prospective study was conducted. All adult patients undergoing CPR admitted to Department of Emergency and intensive care unit (ICU) of Zhengzhou People's Hospital from May 2016 to November 2018 were enrolled. The blood flow over the right carotid arteries during chest compressions was recorded with a bedside ultrasound machine. The peak systolic flow velocity (PSV) and end diastolic flow velocity (EDV) of carotid artery were recorded at 1 minute after the start of CPR and 1 minute before the end of CPR. The mean compression frequency during the whole recovery period was recorded, the rate of compression reaching the standard was evaluated by ultrasound (the rate of compression 100-120 times/min was defined as up to standard), and the interruption time of compression was calculated retrospectively according to the ultrasound image data recorded during CPR. Thirty-nine patients were enrolled, and 21 patients were successfully rescued, with a successful rate of 53.8%, the time of restoration of spontaneous circulation (ROSC) was (10.9±5.3) minutes. The time from CPR to retrieve an ultrasound image was 1.1-4.9 minutes, with an average of (2.5±1.2) minutes. Satisfactory ultra-sonographic images were obtained in 28 patients during the whole course of chest compression. The acquisition rate was 71.8% (28/39). In the process of compression, if the frequency of compression was less than 100 times/min or the velocity of carotid artery dropped (PSV < 30 cm/s), the chest compressors should be reminded and corrected in time. The PSV at 1 minute after CPR start of 28 patients with satisfactory ultrasound images was (62.9±18.5) cm/s, and the EDV was (13.9±3.5) cm/s, the PSV at 1 minute before the end of CPR was (55.4±18.4) cm/s, and the EDV was (12.9±3.7) cm/s. There was no significant difference in above parameters between the two time points (both P > 0.05), suggesting that satisfactory resuscitation effect was achieved in the whole process of CPR. The compression frequency of 28 patients was 100-149 times/min with an average of (117±47) times/min. The rate of compression with standard was 85.7% (24/28), and the total interruption time of compression accounted for 4.4% of all compression time (25.9 minutes/587.2 minutes). Ultrasound measurement of common carotid artery blood flow during CPR has the advantage of real-time and non-invasive, and it is feasible in clinical work.

Noninvasive evaluation of hemodynamics and light scattering property during two-stage mouse cutaneous carcinogenesis based on multispectral diffuse reflectance images at isosbestic wavelengths of hemoglobin.

.We investigate a multispectral imaging method to evaluate spatiotemporal changes in both cutaneous hemoglobin concentration and light scattering parameter in mouse skin through diffuse reflectance spectroscopy using the reflectance images acquired at isosbestic wavelengths of hemoglobin (420, 450, 500, and 585 nm). In the proposed approach, Monte Carlo simulation-based empirical formulas are introduced to extract the scattering power representing the wavelength dependence of light scattering spectrum of skin tissue, as well as the total hemoglobin concentration in dermal vasculatures. The use of isosbestic wavelengths of hemoglobin enables the values of and to be estimated independently of the oxygenation of hemoglobin. Experiments using in vivo mice two-stage chemical carcinogenesis model are performed to confirm the feasibility of the proposed method for evaluating the changes in cutaneous vasculatures and tissue morphology during tumor initiation, promotion, and progression processes. The experimental results reveal that the changes in scattering power of back skin are significantly reduced and followed by the increase in total hemoglobin concentration in the carcinogenesis mice group, which indicates morphological changes in skin tissue such as edema and cell swelling caused by tumor promotion and successive angiogenesis along with tumor progression. The results suggest that the potential of the present method to detect cutaneous carcinogenesis in an early stage and monitor physiological changes during promotion and progression process of nonmelanoma tumors.

Non-invasive hemodynamic evaluation by Doppler echocardiography.

The approach for treating a hemodynamically unstable patient remains a diagnostic and therapeutic challenge. Stabilization of the patient should be rapid and effective, but there is not much room for error. This narrow window of intervention makes it necessary to use rapid and accurate hemodynamic evaluation methods. Echocardiography is the method of choice for the bedside evaluation of patients in circulatory shock. In fact, it was intensive care physicians who recognized the potential of Doppler echocardiography for the initial approach to patients in circulatory failure. An echocardiogram allows rapid anatomical and functional cardiac evaluation, which may include non-invasive hemodynamic evaluation using a Doppler study. Such an integrated study may provide data of extreme importance for understanding the mechanisms underlying the hemodynamic instability of the patient to allow the rapid institution of appropriate therapeutic measures. In the present article, we describe the most relevant echocardiographic findings using a practical approach for critical patients with hemodynamic instability.